Organs on the Left Side

When you look at yourself in a mirror, your body may appear relatively symmetrical, with two eyes, two ears, two arms, and so on. But under the skin, your left and right sides house different internal organs.

Here’s a brief guide to the internal left side of your body, starting at your upper left.

Self-cleaning lungs

Your heart sits in the middle of your chest, to the left. The heart is a muscle at the center of your circulatory system.

The average adult heart is about the size of a fist: 5 inches long, 3.5 inches wide, and 2.5 inches deep.

What it does

The heart pumps blood around your body through a system of blood vessels. The blood delivers oxygen to your brain and the rest of your body and then returns to pick up new oxygen through the lungs.

Your heart has four chambers to do its work:

Two upper chambers called atria, right and left. The right atrium receives oxygen-depleted blood returning from the body (except the lungs). The left atrium receives oxygenated blood returning to the heart from the lungs.

Two lower chambers called ventricles, right and left. The right ventricle pumps the oxygen-depleted blood out to the lungs. The left ventricle pumps the oxygenated blood to the rest of the body (aside from the lungs).

The adrenal cortex is the outer part of the adrenal gland. It produces aldosterone and cortisol, both essential for life.

The adrenal medulla is the inner part of the adrenal gland. It produces hormones that regulate the fight-or-flight response to stress. These include epinephrine (also called adrenaline) and norepinephrine (also called noradrenaline).

Subtle signs from hormones

If a person’s adrenal glands are producing too much or too little of a hormone, the signs of a problem may be subtle. Their blood pressure may be low. Or they can be dizzy or very fatigued.

The replaceable spleen

You have two kidneys located below your rib cage. They’re on either side of your spine, in front of your lowest (floating) ribs.

The kidneys are bean-shaped and about fist-sized. Your left kidney is typically a little larger than the right one.

What it does

The kidneys filter out wastes and extra fluids from your body into urine. Your kidneys help keep the salts and minerals in your blood in proper balance.

The kidneys also make hormones that are important in controlling your blood pressure and producing red blood cells.

Your kidneys have an intricate filtering system. Each kidney has about 1 million filters, called nephrons.

Each nephron has two parts: a renal corpuscle, which contains the glomerulus, and a tubule. The glomerulus filters your blood. The tubule removes waste products and returns essential substances to your blood.

One kidney can do the work of two. You can lead a normal life if you have only one healthy kidney.

Kidneys in history

The ancient Egyptians were aware of the kidneys, according to a papyrus dating back to between 1500 B.C. and 1300 B.C.

Hidden symptoms

There are more than 37,000 new cases of pancreatic cancer per year in the United States, according to the National Pancreas Foundation. A sign of this type of cancer is yellowing of the skin without any other symptoms.

Most of your liver is on the right side of your body. Only a small lobe of the liver is on the left. It’s located above and in front of your stomach and below the diaphragm.

Your liver is about as large as a football and weighs three pounds.

What it does

The liver is a very hardworking organ. The liver:

regulates metabolic functions

generates energy

converts substances

removes toxins

The liver manages chemical levels in the blood and sends some waste products away as urea or within the bile it produces. It processes nutrients, too. It stores some of them, eliminates others, and sends some back to the blood.

The liver also plays a role in breaking down carbohydrates, fats, and proteins and storing vitamins and minerals.

Your liver sends bile out into the small intestine, which helps aid the digestion and absorption of fats into the body. Bile is eliminated in feces. Blood byproducts are sent to the kidneys, where they’re eliminated in your urine.

You can’t live without a liver, but your liver has the ability to regenerate its cells.

Made of lobes

Each lobe of your liver is divided into eight segments. There are about 1,000 smaller lobes in each segment.

Left fallopian tube

The fallopian tube runs between the ovary and the uterus. It’s also known as a uterine tube.

What it does

Eggs travel from the ovary to the uterus via the fallopian tube. It’s where the male sperm meets the egg and fertilizes it.

Did you know?

Fallopian tubes are named for Gabrielis Fallopius (1523–1562), an Italian physician and anatomist who first described the uterine tubes.

Left ovary

One ovary lives on each side of the uterus. Each gland is about the size of an almond.

What it does

During childbearing years, the female body ovulates about once a month, releasing an egg from the ovary. This is usually around the middle of the 28-day menstrual cycle. The egg travels into the fallopian tube and then toward the uterus.

In the reproduction process, a male sperm fertilizes an egg to begin pregnancy.

Did you know?

Your body is a complex living machine with many intricate parts. Important organs are located on your left side.

Did you know?

An estimated 1 in 10,000 people are born with the organs of their left and right sides reversed in what’s called complete situs inversus. This condition was first described in the scientific literature by Matthew Baillie, MD, in 1788.